Network Router User Manual

Web OS 10.0 Application Guide
Chapter 4: OSPF
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212777-A, February 2002
Types of OSPF Routing Devices
As shown in Figure 4-2, OSPF uses the following types of routing devices:
n Internal Router (IR)—a router that has all of its interfaces within the same area. IRs main-
tain LSDBs identical to those of other routing devices within the local area.
n Area Border Router (ABR)—a router that has interfaces in multiple areas. ABRs maintain
one LSDB for each connected area and disseminate routing information between areas.
n Autonomous System Boundary Router (ASBR)—a router that acts as a gateway between
the OSPF domain and non-OSPF domains, such as RIP, BGP, and static routes.
Figure 4-2 OSPF Domain and an Autonomous System
Backbone
Area 0
Area 3
Area 2
Area 1
Inter-Area Routes
(Summary Routes)
ABR
ABR
ABR
ASBR
Internal
Router
ASBR
External
Routes
BGP
RIP
OSPF Autonomous System